Commit ba11ad9a authored by Lars Ellenberg's avatar Lars Ellenberg Committed by Jens Axboe
Browse files

drbd: improve usage of MSG_MORE 



It seems to improve performance if we allow the "p_data" header in its
own frame (no MSG_MORE), but sendpage all but the last page with MSG_MORE.
This is also in preparation of a later zero copy receive implementation.

Suggested by Eduard.Guzovsky@stratus.com on drbd-dev.

Signed-off-by: default avatarPhilipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: default avatarLars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: default avatarJens Axboe <jaxboe@fusionio.com>
parent 5dbf1673

drivers/block/drbd/drbd_main.c

+19 −13
Original line number Diff line number Diff line
@@ -2272,9 +2272,9 @@ static int we_should_drop_the_connection(struct drbd_conf *mdev, struct socket * 
 * with page_count == 0 or PageSlab.

 */

static int _drbd_no_send_page(struct drbd_conf *mdev, struct page *page,

		   int offset, size_t size)

		   int offset, size_t size, unsigned msg_flags)

{

	int sent = drbd_send(mdev, mdev->data.socket, kmap(page) + offset, size, 0);

	int sent = drbd_send(mdev, mdev->data.socket, kmap(page) + offset, size, msg_flags);

	kunmap(page);

	if (sent == size)

		mdev->send_cnt += size>>9;
@@ -2282,7 +2282,7 @@ static int _drbd_no_send_page(struct drbd_conf *mdev, struct page *page, 
}



static int _drbd_send_page(struct drbd_conf *mdev, struct page *page,

		    int offset, size_t size)

		    int offset, size_t size, unsigned msg_flags)

{

	mm_segment_t oldfs = get_fs();

	int sent, ok;
@@ -2295,14 +2295,15 @@ static int _drbd_send_page(struct drbd_conf *mdev, struct page *page, 
	 * __page_cache_release a page that would actually still be referenced

	 * by someone, leading to some obscure delayed Oops somewhere else. */

	if (disable_sendpage || (page_count(page) < 1) || PageSlab(page))

		return _drbd_no_send_page(mdev, page, offset, size);

		return _drbd_no_send_page(mdev, page, offset, size, msg_flags);



	msg_flags |= MSG_NOSIGNAL;

	drbd_update_congested(mdev);

	set_fs(KERNEL_DS);

	do {

		sent = mdev->data.socket->ops->sendpage(mdev->data.socket, page,

							offset, len,

							MSG_NOSIGNAL);

							msg_flags);

		if (sent == -EAGAIN) {

			if (we_should_drop_the_connection(mdev,

							  mdev->data.socket))
@@ -2331,9 +2332,11 @@ static int _drbd_send_bio(struct drbd_conf *mdev, struct bio *bio) 
{

	struct bio_vec *bvec;

	int i;

	/* hint all but last page with MSG_MORE */

	__bio_for_each_segment(bvec, bio, i, 0) {

		if (!_drbd_no_send_page(mdev, bvec->bv_page,

				     bvec->bv_offset, bvec->bv_len))

				     bvec->bv_offset, bvec->bv_len,

				     i == bio->bi_vcnt -1 ? 0 : MSG_MORE))

			return 0;

	}

	return 1;
@@ -2343,12 +2346,13 @@ static int _drbd_send_zc_bio(struct drbd_conf *mdev, struct bio *bio) 
{

	struct bio_vec *bvec;

	int i;

	/* hint all but last page with MSG_MORE */

	__bio_for_each_segment(bvec, bio, i, 0) {

		if (!_drbd_send_page(mdev, bvec->bv_page,

				     bvec->bv_offset, bvec->bv_len))

				     bvec->bv_offset, bvec->bv_len,

				     i == bio->bi_vcnt -1 ? 0 : MSG_MORE))

			return 0;

	}



	return 1;

}
@@ -2356,9 +2360,11 @@ static int _drbd_send_zc_ee(struct drbd_conf *mdev, struct drbd_epoch_entry *e) 
{

	struct page *page = e->pages;

	unsigned len = e->size;

	/* hint all but last page with MSG_MORE */

	page_chain_for_each(page) {

		unsigned l = min_t(unsigned, len, PAGE_SIZE);

		if (!_drbd_send_page(mdev, page, 0, l))

		if (!_drbd_send_page(mdev, page, 0, l,

				page_chain_next(page) ? MSG_MORE : 0))

			return 0;

		len -= l;

	}
@@ -2438,11 +2444,11 @@ int drbd_send_dblock(struct drbd_conf *mdev, struct drbd_request *req) 
	p.dp_flags = cpu_to_be32(dp_flags);

	set_bit(UNPLUG_REMOTE, &mdev->flags);

	ok = (sizeof(p) ==

		drbd_send(mdev, mdev->data.socket, &p, sizeof(p), MSG_MORE));

		drbd_send(mdev, mdev->data.socket, &p, sizeof(p), dgs ? MSG_MORE : 0));

	if (ok && dgs) {

		dgb = mdev->int_dig_out;

		drbd_csum_bio(mdev, mdev->integrity_w_tfm, req->master_bio, dgb);

		ok = drbd_send(mdev, mdev->data.socket, dgb, dgs, MSG_MORE);

		ok = drbd_send(mdev, mdev->data.socket, dgb, dgs, 0);

	}

	if (ok) {

		if (mdev->net_conf->wire_protocol == DRBD_PROT_A)
@@ -2491,11 +2497,11 @@ int drbd_send_block(struct drbd_conf *mdev, enum drbd_packets cmd, 
		return 0;



	ok = sizeof(p) == drbd_send(mdev, mdev->data.socket, &p,

					sizeof(p), MSG_MORE);

					sizeof(p), dgs ? MSG_MORE : 0);

	if (ok && dgs) {

		dgb = mdev->int_dig_out;

		drbd_csum_ee(mdev, mdev->integrity_w_tfm, e, dgb);

		ok = drbd_send(mdev, mdev->data.socket, dgb, dgs, MSG_MORE);

		ok = drbd_send(mdev, mdev->data.socket, dgb, dgs, 0);

	}

	if (ok)

		ok = _drbd_send_zc_ee(mdev, e);

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